Dose-Dependent Biphasic Action of Quetiapine on AMPK Signalling via 5-HT7 Receptor: Exploring Pathophysiology of Clinical and Adverse Effects of Quetiapine.

Recent pharmacological studies indicated that the modulation of tripartite-synaptic transmission plays important roles in the pathophysiology of schizophrenia, mood disorders and adverse reactions. Therefore, to explore the mechanisms underlying the clinical and adverse reactions to atypical antipsychotics, the present study determined the effects of the sub-chronic administration of quetiapine (QTP: 3~30 µM) on the protein expression of 5-HT7 receptor (5-HT7R), connexin43 (Cx43), cAMP level and intracellular signalling, Akt, Erk and adenosine monophosphate-activated protein kinase (AMPK) in cultured astrocytes and the rat hypothalamus, using ultra-high-pressure liquid chromatography with mass spectrometry and capillary immunoblotting systems. QTP biphasically increased physiological ripple-burst evoked astroglial D-serine release in a concentration-dependent manner, peaking at 10 µM. QTP enhanced the astroglial signalling of Erk concentration-dependently, whereas both Akt and AMPK signalling's were biphasically enhanced by QTP, peaking at 10 µM and 3 µM, respectively. QTP downregulated astroglial 5-HT7R in the plasma membrane concentration-dependently. Protein expression of Cx43 in astroglial cytosol and intracellular cAMP levels were decreased and increased by QTP also biphasically, peaking at 3 µM. The dose-dependent effects of QTP on the protein expression of 5-HT7R and Cx43, AMPK signalling and intracellular cAMP levels in the hypothalamus were similar to those in astrocytes. These results suggest several complicated pharmacological features of QTP. A therapeutically relevant concentration/dose of QTP activates Akt, Erk and AMPK signalling, whereas a higher concentration/dose of QTP suppresses AMPK signalling via its low-affinity 5-HT7R inverse agonistic action. Therefore, 5-HT7R inverse agonistic action probably plays important roles in the prevention of a part of adverse reactions of QTP, such as weight gain and metabolic complications.

Short-term quetiapine treatment alters the use of reinforcement signals during risky decision-making and promotes the choice of negative expected values in healthy adult males.

Effective decision-making can involve using environmental signals about the possible good and bad outcomes, and their probabilities, to select optimal actions. Problematic decision-making in psychiatric disorders, and particularly bipolar illness, may result from disrupted use of these reinforcement cues, leading to actions that reflect or precipitate pathological changes in mood. Previous experiments indicate that the processing of reinforcement cues while selecting between risky actions can be influenced by dopamine and serotonin activity. Quetiapine is an atypical antipsychotic agent with a complex pharmacology, including antagonist actions at 5-HT2A and, to a lesser extent, D2 receptors. Here, we investigated the effects of (short-term) treatment with quetiapine on the risky decision-making of healthy human adults. Twenty participants received 150 mg of quetiapine XL for 7 d, whereas 20 age- and IQ-matched participants received a placebo. On the eighth day, all participants completed a risky decision-making task that involved making a series of choices between two simultaneously presented gambles that differed in the magnitudes of their possible gains and losses, and the probabilities with which these outcomes were delivered. Quetiapine treatment was associated with a marked tendency to choose options with negative expected values compared with placebo treatment in male but not female participants. Our results demonstrate that antagonism of serotonin and dopamine receptor activity can alter the way individuals use information about gains and losses when selecting between risky actions, possibly reflecting gender-specific differences in risk attitudes. These effects may be beneficial by correcting decision-making biases that feature in mood disorders.

Astrocyte-dependent protective effect of quetiapine on GABAergic neuron is associated with the prevention of anxiety-like behaviors in aging mice after long-term treatment.

Previous studies have demonstrated that quetiapine (QTP) may have neuroprotective properties; however, the underlying mechanisms have not been fully elucidated. In this study, we identified a novel mechanism by which QTP increased the synthesis of ATP in astrocytes and protected GABAergic neurons from aging-induced death. In 12-month-old mice, QTP significantly improved cell number of GABAegic neurons in the cortex and ameliorated anxiety-like behaviors compared to control group. Complimentary in vitro studies showed that QTP had no direct effect on the survival of aging GABAergic neurons in culture. Astrocyte-conditioned medium (ACM) pretreated with QTP (ACMQTP) for 24 h effectively protected GABAergic neurons against aging-induced spontaneous cell death. It was also found that QTP boosted the synthesis of ATP from cultured astrocytes after 24 h of treatment, which might be responsible for the protective effects on neurons. Consistent with the above findings, a Rhodamine 123 test showed that ACMQTP, not QTP itself, was able to prevent the decrease in mitochondrial membrane potential in the aging neurons. For the first time, our study has provided evidence that astrocytes may be the conduit through which QTP is able to exert its neuroprotective effects on GABAergic neurons. The neuroprotective properties of quetiapine (QTP) have not been fully understood. Here, we identify a novel mechanism by which QTP increases the synthesis of ATP in astrocytes and protects GABAergic neurons from aging-induced death in a primary cell culture model. In 12-month-old mice, QTP significantly improves cell number of GABAegic neurons and ameliorates anxiety-like behaviors. Our study indicates that astrocytes may be the conduit through which QTP exerts its neuroprotective effects on GABAergic neurons.

Quetiapine and aripiprazole signal differently to ERK, p90RSK and c-Fos in mouse frontal cortex and striatum: role of the EGF receptor.

BACKGROUND: Signaling pathways outside dopamine D2 receptor antagonism may govern the variable clinical profile of antipsychotic drugs (APD) in schizophrenia. One postulated mechanism causal to APD action may regulate synaptic plasticity and neuronal connectivity via the extracellular signal-regulated kinase (ERK) cascade that links G-protein coupled receptors (GPCR) and ErbB growth factor signaling, systems disturbed in schizophrenia. This was based upon our finding that the low D2 receptor affinity APD clozapine induced initial down-regulation and delayed epidermal growth factor receptor (EGFR or ErbB1) mediated activation of the cortical and striatal ERK response in vivo distinct from olanzapine or haloperidol. Here we map whether the second generation atypical APDs aripiprazole and quetiapine affect the EGFR-ERK pathway and its substrates p90RSK and c-Fos in mouse brain, given their divergent agonist and antagonist properties on dopaminergic transmission, respectively. RESULTS: In prefrontal cortex, aripiprazole triggered triphasic ERK phosphorylation that was EGFR-independent but had no significant effect in striatum. Conversely quetiapine did not alter cortical ERK signaling but elevated striatal ERK levels in an EGFR-dependent manner. Induction of ERK by aripiprazole did not affect p90RSK signaling but quetiapine decreased RSK phosphorylation within 1-hour of administration. The transcription factor c-Fos by comparison was a direct target of ERK phosphorylation induced by aripiprazole in cortex and quetiapine in striatum with protein levels in temporal alignment with that of ERK. CONCLUSIONS: These data indicate that aripiprazole and quetiapine signal to specific nuclear targets of ERK, which for quetiapine occurs via an EGFR-linked mechanism, possibly indicating involvement of this system in its action.

Quetiapine attenuates glial activation and proinflammatory cytokines in APP/PS1 transgenic mice via inhibition of nuclear factor-κB pathway.

BACKGROUND: In Alzheimer's disease, growing evidence has shown that uncontrolled glial activation and neuroinflammation may contribute independently to neurodegeneration. Antiinflammatory strategies might provide benefits for this devastating disease. The aims of the present study are to address the issue of whether glial activation and proinflammatory cytokine increases could be modulated by quetiapine in vivo and in vitro and to explore the underlying mechanism. METHODS: Four-month-old amyloid precursor protein (APP) and presenilin 1 (PS1) transgenic and nontransgenic mice were treated with quetiapine (5mg/kg/d) in drinking water for 8 months. Animal behaviors, total Aß levels, and glial activation were evaluated by behavioral tests, enzyme-linked immunosorbent assay, immunohistochemistry, and Western blot accordingly. Inflammatory cytokines and the nuclear factor kappa B pathway were analyzed in vivo and in vitro. RESULTS: Quetiapine improves behavioral performance, marginally affects total Aß40 and Aß42 levels, attenuates glial activation, and reduces proinflammatory cytokines in APP/PS1 mice. Quetiapine suppresses Aß1-42-induced activation of primary microglia by decresing proinflammatory cytokines. Quetiapine inhibits the activation of nuclear factor kappa B p65 pathway in both transgenic mice and primary microglia stimulated by Aß1-42. CONCLUSIONS: The antiinflammatory effects of quetiapine in Alzheimer's disease may be involved in the nuclear factor kappa B pathway. Quetiapine may be an efficacious and promising treatment for Alzheimer's disease targeting on neuroinflammation.

Effect of quetiapine on Per1, Per2, and Bmal1 clock gene expression in the mouse amygdala and hippocampus.

Circadian rhythms are related to various psychiatric disorders. Recently, antipsychotics, including quetiapine (QTP), have been accepted as potential therapeutic agents for the treatment of depression, but its mechanism remains poorly understood. In this study, we examined clock gene fluctuation patterns in QTP-treated mice. QTP significantly increased Per2 mRNA at ZT12 and Per1 and Per2 expression at ZT18 in the amygdala. There were significant differences between the control and QTP groups in the cross-time effects of Per2 mRNA expression in the amygdala. Our findings suggest that QTP possibly acts on the circadian system, which then induces changes in mood symptoms.

Extended-release quetiapine fumarate (quetiapine XR) as adjunctive therapy in patients with generalized anxiety disorder and a history of inadequate treatment response: a randomized, double-blind study.

BACKGROUND: For many patients with generalized anxiety disorder (GAD), first-line treatment does not lead to remission. This study investigated the efficacy and tolerability of adjunctive extended-release quetiapine fumarate (quetiapine XR) in patients with GAD and an inadequate response to selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs). METHODS: Patients were randomized to quetiapine XR or placebo adjunctive to SSRI/SNRIs in an 11-week study. The primary endpoint was change from randomization to week 8 in Hamilton Anxiety Rating Scale (HAM-A) total score. Secondary variables were HAM-A psychic/somatic clusters, response, and remission, and Clinical Global Impression­Severity of Illness (CGI-S) score. RESULTS: A total of 409 patients received quetiapine XR (n=209) or placebo (n=200). The week 8 mean change in HAM-A total score was not statistically significant for quetiapine XR (­10.74; P=.079) vs placebo (­9.61). Secondary variables were generally consistent with the primary analysis, except for a significant reduction in HAM-A total score (week 1) and significant improvements in HAM-A psychic cluster and CGI-S total scores (week 8). Adverse events included dry mouth, somnolence, sedation, headache, and dizziness. CONCLUSIONS: In patients with GAD and an inadequate response to SSRI/SNRIs, adjunctive quetiapine XR did not show a statistically significant effect for the primary endpoint at week 8, although some secondary endpoints were statistically significant vs placebo. Quetiapine XR was generally well tolerated.

Identification of a suitable and selective inhibitor towards aldehyde oxidase catalyzed reactions.

1. Aldehyde oxidase (AO) is a liver cytosolic molybdoflavoprotein enzyme whose importance in drug metabolism is gaining in the recent. The objective of this work is to find a potent and selective inhibitor for AO activity using phthalazine oxidation as a marker reaction. 2. Among organic solvents tested, it was identified that methanol was not a suitable choice for AO activity even at concentrations less than 0.2% v/v. Acetonitrile and DMSO did not show any effect till 0.5% v/v but thereafter activites tend to decrease. 3. For selectivity, 23 compounds were selected and evaluated for their effects on AO and nine CYP450 enzymes. Among the tested compounds chlorpromazine, estradiol, hydralazine, quetiapine and raloxifene were selected based on their potency of inhibition towards AO activity. 4. Raloxifene was found to be a non-specific inhibitor of all major tested CYP450 enzymes and was excluded as a selective inhibitor for AO. Quetiapine also showed a degree of inhibition towards the major CYP450 tested. Hydralazine used as a specific inhibitor during the past for AO activity demonstrated a stimulation of AO activity at high and low concentrations respectively and the inhibition noted to be time dependent while inhibiting other enzymes like monoamine oxidase. 5. Estradiol showed no inhibition towards the tested CYP450 enzymes and thus proved to be a selective and specific inhibitor for AO activity with an uncompetitive mode of inhibition.

Quetiapine modulates functional connectivity in brain aggression networks.

Aggressive behavior is associated with dysfunctions in an affective regulation network encompassing amygdala and prefrontal areas such as orbitofrontal (OFC), anterior cingulate (ACC), and dorsolateral prefrontal cortex (DLPFC). In particular, prefrontal regions have been postulated to control amygdala activity by inhibitory projections, and this process may be disrupted in aggressive individuals. The atypical antipsychotic quetiapine successfully attenuates aggressive behavior in various disorders; the underlying neural processes, however, are unknown. A strengthened functional coupling in the prefrontal-amygdala system may account for these anti-aggressive effects. An inhibition of this network has been reported for virtual aggression in violent video games as well. However, there have been so far no in-vivo observations of pharmacological influences on corticolimbic projections during human aggressive behavior. In a double-blind, placebo-controlled study, quetiapine and placebo were administered for three successive days prior to an fMRI experiment. In this experiment, functional brain connectivity was assessed during virtual aggressive behavior in a violent video game and an aggression-free control task in a non-violent modification. Quetiapine increased the functional connectivity of ACC and DLPFC with the amygdala during virtual aggression, whereas OFC-amygdala coupling was attenuated. These effects were observed neither for placebo nor for the non-violent control. These results demonstrate for the first time a pharmacological modification of aggression-related human brain networks in a naturalistic setting. The violence-specific modulation of prefrontal-amygdala networks appears to control aggressive behavior and provides a neurobiological model for the anti-aggressive effects of quetiapine.

Neural markers of negative symptom outcomes in distributed working memory brain activity of antipsychotic-naive schizophrenia patients.

Since working memory deficits in schizophrenia have been linked to negative symptoms, we tested whether features of the one could predict the treatment outcome in the other. Specifically, we hypothesized that working memory-related functional connectivity at pre-treatment can predict improvement of negative symptoms in antipsychotic-treated patients. Fourteen antipsychotic-naive patients with first-episode schizophrenia were clinically assessed before and after 7 months of quetiapine monotherapy. At baseline, patients underwent functional magnetic resonance imaging while performing a verbal n-back task. Spatial independent component analysis identified task-modulated brain networks. A linear support vector machine was trained with these components to discriminate six patients who showed improvement in negative symptoms from eight non-improvers. Classification accuracy and significance was estimated by leave-one-out cross-validation and permutation tests, respectively. Two frontoparietal and one default mode network components predicted negative symptom improvement with a classification accuracy of 79% (p = 0.003). Discriminating features were found in the frontoparietal networks but not the default mode network. These preliminary data suggest that functional patterns at baseline can predict negative symptom treatment-response in schizophrenia. This information may be used to stratify patients into subgroups thereby facilitating personalized treatment.

Pharmacotherapy response and regional cerebral blood flow characteristics in patients with obsessive-compulsive disorder.

OBJECTIVE: To analyze the correlation between the pharmacotherapy response and the characteristics of the pre-treatment regional cerebral blood flow (rCBF) in patients with obsessive-compulsive disorder (OCD). METHODS: Single-photon emission-computed tomography (SPECT) was used to determine the pre-treatment rCBF in 30 OCD patients and 30 normal controls. Based on their clinical remission response, the subjects were divided into two groups: selective serotonin reuptake inhibitors (SSRIs) and SSRIs plus quetiapine. The subjects with clinical remission response were identified after treatment for a period of 24 weeks, and the rCBF imaging data were processed using statistical parametric mapping (SPM) software with two-sample Z-tests. RESULTS: Nineteen OCD patients who achieved clinical remission were included in the study. Increased rCBF in forebrain regions, including the frontal lobe, cingulate gyrus, hypothalamus, and basal ganglia, was found in 11 responders to SSRIs compared to normal control patients. The eight SSRI plus quetiapine responders exhibited a decrease in rCBF within posterior brain regions, including the parietal lobe, cerebellar vermis, and occipital lobe, and an increase in rCBF in the frontal lobe, thalamus, basal ganglia, and cerebellum tonsil compared to normal control patients. CONCLUSIONS: The characteristics of increased rCBF in forebrain regions and decreased rCBF in posterior brain regions before treatment of OCD patients was a potentially predictor of treatment response to guide treatment options.

Maintenance treatment with quetiapine when combined with either lithium or divalproex in bipolar I disorder: analysis of two large randomized, placebo-controlled trials.

BACKGROUND: To determine the efficacy and safety of quetiapine combined with lithium or divalproex for preventing mood events in patients with bipolar I disorder. In this pooled analysis of two similar long-term studies (D1447C00126 [NCT00107731] and D1447C00127 [NCT00081380]), lithium and divalproex treatment groups were analyzed separately. METHODS: Patients received open-label quetiapine (400-800 mg/d) plus lithium or divalproex to achieve ≥12 weeks of clinical stability before being randomized to double-blind combination treatment with quetiapine (400-800 mg/d) or placebo plus lithium or divalproex for up to 104 weeks. The primary endpoint was time to first mood event postrandomization following open stabilization. RESULTS: Of 3,414 patients in the stabilization phase, 1,326 were randomized. There were no differences in the risk of recurrence of mood, mania, or depression between quetiapine plus lithium or quetiapine plus divalproex. Among patients co-treated with placebo and lithium, the risk of recurrence of a mania event was significantly higher than among patients co-treated with placebo and divalproex. In patients with an index episode of mania, placebo plus lithium was associated with a significantly higher risk of recurrence of a mania event than placebo plus divalproex. Safety data were generally consistent with recognized safety profiles. CONCLUSIONS: In patients with bipolar I disorder previously stabilized on quetiapine and lithium or divalproex, maintenance therapy with quetiapine significantly increased the time to recurrence of a mood event (mania or depression) versus placebo, regardless of whether it was combined with lithium or divalproex.

Extended-release quetiapine fumarate (quetiapine XR) as adjunctive therapy in patients with generalized anxiety disorder and a history of inadequate treatment response: a randomized, double-blind study.

BACKGROUND: For many patients with generalized anxiety disorder (GAD), first-line treatment does not lead to remission. This study investigated the efficacy and tolerability of adjunctive extended-release quetiapine fumarate (quetiapine XR) in patients with GAD and an inadequate response to selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs). METHODS: Patients were randomized to quetiapine XR or placebo adjunctive to SSRI/SNRIs in an 11-week study. The primary endpoint was change from randomization to week 8 in Hamilton Anxiety Rating Scale (HAM-A) total score. Secondary variables were HAM-A psychic/somatic clusters, response, and remission, and Clinical Global Impression­Severity of Illness (CGI-S) score. RESULTS: A total of 409 patients received quetiapine XR (n = 209) or placebo (n = 200). The week 8 mean change in HAM-A total score was not statistically significant for quetiapine XR (­10.74; P = .079) vs placebo (­9.61). Secondary variables were generally consistent with the primary analysis, except for a significant reduction in HAM-A total score (week 1) and significant improvements in HAM-A psychic cluster and CGI-S total scores (week 8). Adverse events included dry mouth, somnolence, sedation, headache, and dizziness. CONCLUSIONS: In patients with GAD and an inadequate response to SSRI/ SNRIs, adjunctive quetiapine XR did not show a statistically significant effect for the primary endpoint at week 8, although some secondary endpoints were statistically significant vs placebo. Quetiapine XR was generally well tolerated.

Changes in QT interval after switching to quetiapine in Japanese patients with schizophrenia.

OBJECTIVES: There are few reports regarding quetiapine (QTP)-related QT prolongation. We examined the change in QT interval after switching from aripiprazole (ARP), olanzapine (OLZ), or risperidone (RIS) to QTP. METHODS: Twenty subjects treated with ARP, OLZ, or RIS were enrolled in the study. Following baseline assessments, which included QT interval and electrolytes, these three drugs were switched to QTP for each subject. The same parameters were evaluated following a switch to QTP. RESULTS: All 20 patients who had been treated with ARP, OLZ, or RIS were successfully switched to QTP. Significant increases were observed in the total mean corrected QT (QTc) interval after switching (p = 0.014). The coefficient of variation for the extent of change in QTc interval was 1.66. The mean QTc with ARP treatment was significantly increased after QTP treatment (p = 0.004). CONCLUSIONS: Quetiapine might have a greater effect on QTc interval than other second-generation antipsychotics. However, because there was a considerable variability in the extent of QTc prolongation after switch to QTP, further studies are required to clarify the effect of QTP on QTc interval.

A human laboratory study investigating the effects of quetiapine on marijuana withdrawal and relapse in daily marijuana smokers.

Marijuana withdrawal contributes to the high relapse rates in individuals seeking treatment for marijuana-use disorders. Quetiapine, an atypical antipsychotic, reduces characteristic symptoms of marijuana withdrawal in a variety of psychiatric conditions, including mood lability, sleep disruption and anorexia. This human laboratory study investigated the effectiveness of quetiapine to decrease marijuana withdrawal and relapse to marijuana use in non-treatment-seeking marijuana smokers. Volunteers were maintained on placebo or quetiapine (200 mg/day) in this double-blind, counter-balanced, within-subject study consisting of two 15-day medication phases, the last 8 days of which were in-patient. On the first in-patient day, active marijuana [6.2% delta (9)-tetrahydrocannabinol (THC)] was repeatedly smoked under controlled conditions. For the next 3 days, inactive marijuana (0.0% THC) was available for self-administration (withdrawal). On the subsequent 4 days, active marijuana (6.2% THC) was available for self-administration (relapse). Volunteers (n = 14) who smoked an average of 10 marijuana cigarettes/day, 7 days/week, completed the study. Under placebo, withdrawal was marked by increased subjective ratings of negative mood, decreased sleep quality, and decreased caloric intake and weight loss. Compared with placebo, quetiapine improved sleep quality, increased caloric intake and decreased weight loss. However, quetiapine increased marijuana craving and marijuana self-administration during the relapse phase. These data do not suggest that quetiapine shows promise as a potential treatment for marijuana dependence.

Quetiapine as combination treatment with citalopram in unipolar depression with prominent somatic symptoms: a randomised, double-blind, placebo-controlled pilot study.

BACKGROUND: Patients with major depressive disorder (MDD) accompanied by physical symptoms may be less responsive to antidepressant treatment. Quetiapine has been evaluated in the treatment of bipolar depression and has been recently approved as an add-on therapy for unipolar depression. Less is known about the efficacy of combination therapies in patients suffering from MDD with somatic symptoms. The aim of the present study was to evaluate the efficacy of quetiapine as adjunctive therapy to the SSRI citalopram in patients with MDD and somatic complaints. SUBJECTS AND METHODS: 41 inpatients with nonpsychotic DSM-IV MDD experiencing significant symptoms of somatic distress as defined by a baseline score on the SCL-90-R somatization subscale greater one standard deviation above adult nonpatient norms were randomly assigned to receive either citalopram 40 mg/day plus placebo (n=20) or citalopram 40 mg/day plus quetiapine, 300 to 600 mg/day (n=21) for 6 weeks. The primary outcome measure was the Hamilton Depression Rating Scale (HDRS) score. RESULTS: Mean changes in HDRS scores from baseline to week 6 using last-observation-carried-forward methods were -12.3±6.2 and -10.7±5.1 in the citalopram-quetiapine and citalopram-placebo group, respectively. Remission rates were significant higher in the citalopram-quetiapine-group (41.1%) than in the citalopram-placebo-group (26.3%), respectively. CONCLUSIONS: Although quetiapine as add-on to citalopram did not separate statistically from placebo on the HDRS score in improving depressive symptoms and somatic symptoms in patients with MDD and prominent somatic complaints, higher remission rates and other second outcome parameters showed advantages for quetiapine. Larger, double-blind, placebo-controlled trials of quetiapine as augmentation therapy in MDD with somatic symptoms are warranted.

Slow dissociation of partial agonists from the D2 receptor is linked to reduced prolactin release.

In this study we investigated the correlation between affinity, efficacy, peripheral receptor occupancy, and kinetic properties of D2 dopamine receptor ligands with time-course evaluations of prolactin release in rat blood. We profiled typical and atypical antipsychotic antagonists at D2 receptors, the partial agonist aripiprazole, and four novel partial agonist compounds with different properties. Clozapine and quetiapine revealed lower prolactin release and fast dissociation kinetics, linking fast dissociation and prolactin-sparing properties. Surprisingly, haloperidol, a highly prolactin-releasing antagonist, shared intermediate dissociation properties. Factors other than kinetic properties may thus contribute to prolactin-releasing properties of antagonists. Partial agonists sharing similar efficacies and receptor occupancies differed markedly in their ability to induce hyperprolactinaemia. Aripiprazole moderately released prolactin even at high receptor occupancies, with slow dissociation from D2 receptors. Other compounds displaying low affinities and fast dissociations released prolactin substantially, although less than haloperidol. The effect augmented after repeated administrations. Compounds with high affinities and slow dissociation rates stimulated moderate prolactin release at high receptor occupancies, reaching a ceiling effect at 50-60% occupancy. Moreover, the effect developed tolerance. In conclusion, we investigated the affinity and kinetic properties of D2 partial agonists associated with their ability to induce prolactin release in blood. We propose that for D2 partial agonists, at comparable intrinsic activities and peripheral occupancies, the prolactin-releasing properties are linked to their kinetic rate properties. Differently from D2 antagonists, partial agonists display slow dissociation and high affinity associated with a low prolactin release profile.

Determining the efficacy and tolerance of quetiapine extended release for the management of psychosis and accompanying acute behavioral disturbance in adult acute psychiatry.

BACKGROUND: This study was conducted to explore the efficacy and tolerability of quetiapine extended release (XR) to treat psychosis and accompanying acute behavioral disturbance in hospitalized psychiatric patients. METHODS: Patients with psychosis who displayed aggression were administered quetiapine XR (day 1 mean dose: 293.3 mg). Symptoms and side effects were assessed prospectively over an 8-day period. Symptoms were measured by the Overt Aggression Scale and Brief Psychiatric Rating Scale (BPRS), and side effects were measured using the Simpson-Angus Scale and Barnes Akathisia Rating Scale. RESULTS: Fifteen of 16 consenting patients completed the study. Aggression was significantly reduced by day 3. Psychopathology also was significantly reduced, with the greatest improvement in BPRS Thinking Disturbance subscale scores. No significant increase in movement side effects was seen by day 8. Seven participants were administered a concomitant sedating antipsychotic on an as-needed basis, particularly in the first 4 days of treatment; these participants displayed much greater aggression--but not psychopathology--at day 1, and it took longer for their aggression and psychopathology to improve compared with patients treated with quetiapine XR as the sole antipsychotic. CONCLUSIONS: Further research is needed before definitive recommendations can be made. However, current findings provide tentative support for quetiapine XR as a safe and effective medication for treating concurrent psychosis and behavioral disturbance, particularly in less severely aggressive patients.

Driving ability under sertindole.

INTRODUCTION: Fitness to drive is an important prerequisite for the functional autonomy and thus also relevant for patients with a psychiatric illness. The efficacy of sertindole in the treatment of positive and negative schizophrenia symptoms has been shown in various studies. However, hitherto there exist no data about patients' fitness to drive under sertindole. METHODS: A non-randomized clinical study with 30 schizophrenic inpatients receiving sertindole (n=10), risperidone (n=10) or quetiapine (n=10) was conducted. Patients were tested under steady-state plasma level conditions prior to discharge to outpatient treatment. Data were collected with the computerized Act and React Testsystem (ART90) and the Wiener Determinationsgerät (WDG) measuring psychomotor skills relevant for fitness to drive. RESULTS: The main findings of this study are (i) that about 26% of schizophrenic patients, -following psychopathologic stabilization and prior discharge to outpatient treatment show severe impairments with respect to driving skills. (ii) Statistically significant differences between atypical antipsychotics could neither be demonstrated on the level of the global driving ability score nor on individual functional domains essential for fitness to drive. CONCLUSION: With respect to driving skills no differences have been found between patients treated with sertindole, risperidone or quetia-pine. However, a great proportion of schizophrenic patients partly remitted must be considered as unfit to drive, even when stabilized on treatment with atypical antipsychotics.